"Essentially the Scrap-o-Matic 1000 works like the Obliterum Forge in Legion however one major difference from Legion is that you can use it to break down any gear obtained that is from the Battle for Azeroth expansion, including dungeon/raid drops, quest rewards, world drops and crafted gear. Apart from a chance at getting Expulsom you will also get ore, gems, leather, occasional enchanting mats (from scrapping cloth gear) and other crafting mats. The best way to obtain Expulsom seems to be from breaking down rare/epic gear you obtain from dungeons and raids, killing rare elites and doing world quests, it also drops rarely from BFA uncommon quality items."
As is true of most web sites, the Company gathers certain information automatically and stores it in log files. This information includes internet protocol (IP) addresses, browser type, internet services provider (ISP), referring/exit pages, operating system, date/time stamp, and clickstream data. The Company uses this information to analyze trends, to screen for fraud, to administer the Company's sites, to track users' movements around the web sites and to gather demographic information about the Company's user base as a whole.
The expansion brings a major change to the PvP ruleset on each realm. Every realm by default only allows players to attack NPCs in the open world; players who wish to engage in world PvP now have a setting called "War Mode" that can only be toggled on or off in their faction's capital city (i.e. Stormwind for the Alliance and Orgrimmar for the Horde). While in War Mode, players have access to new talents and abilities, as well as a slightly accelerated rate of XP gain.[10] Characters with War Mode activated are only able to see other players with War Mode, unless in their own capital cities. 

I think what you're actually talking about when you say "niche" is the barrier to entry for new players. It sounds like you're worried that new players can pick up crafting professions and compete easier than before. Again, I'd say that the alpha build info in the OP looks pretty much the same as the current expansion. The true barrier to entry isn't the ability to level the profession quickly, it's actually recipe ranks. Some really good examples of this in the current expansion are rank 3 bracers, rank 3 flasks, and rank 3 felwort. It takes a certain level of investment to get those ranks, and the goblin activities related to those crafts simply aren't profitable/competitive without rank 3.
I think that's server dependant. I make a lot of Golems, but the price on my server is high enough that you could buy all the living steel and still make about 20K (almost 200kg on AH). Its just that you proc all the way up the chain. You proc 20% of your trillium, and then 20% of your living steel. SoH and Ghost Iron are such low effort farms, too. 20% of 180 Trillium Bars at 500g is 18k more profit, 20% of 150 Living Steel at 3500g is another 105kg. That's an extra 25k profit per Golem. If they stop selling stockpile them for the next expansion, they always boom with the price of herbs. And a consistent 20% proc rate is the opposite of RNG, its extra free stuff as a benefit to completing an extra quest (not to mention for new alchemists the investment of leveling Vanilla Alchemy). You're looking for some get rich quick scheme, where the real way to build wealth is patience and volume. No market is going to be viable because you want it to be. Only because you make it viable.